This disclosure relates generally to water and wastewater treatment equipment and more particularly to energy dissipating fluid inlets for use with clarifiers that are used for clarifying water and wastewater through sedimentation of flocculated and suspended solids. In particular the disclosure is directed to a method and apparatus for evenly and uniformly distributing and dissipating the inlet velocity or energy of the fluid influent that is directed into a clarifier in order to enhance sedimentation of the suspended, flocculated solids and precipitated dissolved solids carried by the influent.
In the treatment of water and wastewater, clarifiers are commonly used for the separation and settling of solids in order to clarify the liquid. In order for some solids to settle, particulates in the influent must be allowed to flocculate and form larger floc that can be more readily settled. The influent is typically introduced into the clarifier through an influent feed structure. The influent energy must be dissipated after flocculation has occurred to prevent shearing of the enlarged floc particles and to enhance sedimentation. The influent must be evenly and uniformly distributed as it enters the clarifier in order to prevent short circuiting of the desired flow path resulting in carry over of solids that would have otherwise settled out of the fluid.
To this end various methods and mechanisms for distributing flow and reducing the process stream velocity or energy have been developed. In rectangular clarifiers the feed structure may take the form of a feed pipe or a feed trough. The influent is admitted into the clarifier through ports that may be vertically or horizontally oriented in the feed structure. The influent may be redirected upon leaving the port by a deflector or a series of deflectors. Alternatively, the influent may be admitted without redirection.
In a circular clarifier the feed structure may take the form of a central influent column, a feed pipe, or a feed trough. An inlet well, that takes the form of a cylindrical ring and a bottom wall generally centered in the circular clarifier, receives influent. In order to enhance flocculation influent energy is required; however, this energy impedes sedimentation or settling of floc. It is helpful to minimize the energy of the influent that enters the inlet well to enhance settling and reduce shearing of the floc particles after they have been formed. Even and uniform distribution of the influent fluid into the clarifier basin reduces short circuiting and carry over of settleable solids into the effluent.
The energy dissipating and uniform distribution of the inlet of the current disclosure as applied to circular clarifiers overcomes the lack of variation or adaptability between tangential or rotational, radial or longitudinal, and impinging flows found in the prior art. This is accomplished with less structure and therefore less expense than the structures of the prior art. Flows can be adapted to the process requirements to combine any or all of tangential, radial, longitudinal, and impinging and non-impinging flows to dissipate energy. Applied to circular clarifiers, unpaired tangential flows from adjacent port sets establishes fluid rotation about the basin vertical center axis. Radial flows resulting from ports selectively adjusted establish fluid motion toward or away from the basin vertical center axis. Additionally, flow can be directed vertically upward or downward.
Applied to rectangular clarifiers, the energy dissipating and uniform distribution inlet of the current disclosure overcomes the lack of variation or adaptability between rotational, longitudinal, impinging, and non-impinging flows found in the prior art. This is accomplished again with less structure and therefore less expense than the structures of the prior art. Flows can be adapted to the process requirements to combine any or all of rotational, longitudinal, impinging, and non-impinging flows to dissipate energy and uniformly distribute the influent stream. Additionally, flow can be directed vertically upward or downward as well as longitudinally toward either end of the basin.
Thus the inlet arrangement of the current disclosure overcomes the disadvantages of the previous designs while maintaining flexibility and at reduced cost of materials and fabrication compared to the previous designs as applied to circular and rectangular clarifiers.
These goals are obtained by dividing the flow through an inlet side wall port into a plurality of flow streams. This is accomplished in the simplest arrangement by dividing the flow through the port into two flow streams by placing deflectors substantially centered on the port and supported from the well side wall by an attachment device. The attachment device and the deflectors then divide the initial flow through the port into two substantially equal flow streams that can be independently directed. Thus the flow is divided and redirected into more evenly and uniformly distributed flow streams, but also may be directed in any one of several directions to dissipate energy, effect fluid rotation or stream impingement of adjacent flow streams from adjacent ports.
It should be understood that the flow through the port can be likewise divided into a larger number of flow streams. The reasonable upper limit on the number of flow streams developed may be three or four for most applications, though in some applications the number of flow streams developed may be considerably higher.
Further, the port may itself be divided into a plurality of smaller ports having a total area substantially the same as the original port. This may be accomplished by ligatures, which then subdivide the original port area into smaller sub-ports. The deflector attachment devices may then also be attached to the ligature or to the wall beyond the ports. Clusters or groupings of at least two sub-ports would then replace the original single port. Additionally, a similar division of influent flow can be accomplished with ports and flow through the bottom wall of the inlet well.